RESUMO
Diabetes is a metabolic disease characterized by high fasting-glucose levels. Diabetic complications have been associated with hyperglycemia and high levels of reactive compounds, such as methylglyoxal (MG) and advanced glycation endproducts (AGEs) formation derived from glucose. Diabetic patients have a higher risk of developing neurodegenerative diseases, such as Alzheimer's disease or Parkinson's disease. Herein, we examined the effect of high glucose, MG and carboxyethyllysine (CEL), a MG-derived AGE of lysine, on oxidative, metabolic and astrocyte-specific parameters in acute hippocampal slices, and investigated some of the mechanisms that could mediate these effects. Glucose, MG and CEL did not alter reactive oxygen species (ROS) formation, glucose uptake or glutamine synthetase activity. However, glutamate uptake and S100B secretion were decreased after MG and CEL exposure. RAGE activation and glycation reactions, examined by aminoguanidine and L-lysine co-incubation, did not mediate these changes. Acute MG and CEL exposure, but not glucose, were able to induce similar effects on hippocampal slices, suggesting that conditions of high glucose concentrations are primarily toxic by elevating the rates of these glycation compounds, such as MG, and by generation of protein cross-links. Alterations in the secretion of S100B and the glutamatergic activity mediated by MG and AGEs can contribute to the brain dysfunction observed in diabetic patients.
Assuntos
Diabetes Mellitus/metabolismo , Ácido Glutâmico/metabolismo , Hipocampo/metabolismo , Lisina/análogos & derivados , Aldeído Pirúvico/farmacologia , Subunidade beta da Proteína Ligante de Cálcio S100/metabolismo , Animais , Astrócitos/metabolismo , Transporte Biológico/efeitos dos fármacos , Metabolismo Energético/efeitos dos fármacos , Glucose/farmacologia , Glutamato-Amônia Ligase/metabolismo , Hiperglicemia/patologia , Lisina/farmacologia , Masculino , Oxirredução/efeitos dos fármacos , Ratos , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismo , Receptor para Produtos Finais de Glicação Avançada/metabolismoRESUMO
Diabetic patients and streptozotocin (STZ)-induced diabetes mellitus (DM) models exhibit signals of brain dysfunction, evidenced by neuronal damage and memory impairment. Astrocytes surrounding capillaries and synapses modulate many brain activities that are connected to neuronal function, such as nutrient flux and glutamatergic neurotransmission. As such, cognitive changes observed in diabetic patients and experimental models could be related to astroglial alterations. Herein, we investigate specific astrocyte changes in the rat hippocampus in a model of DM induced by STZ, particularly looking at glial fibrillary acidic protein (GFAP), S100B protein and glutamate uptake, as well as the content of advanced glycated end products (AGEs) in serum and cerebrospinal fluid (CSF), as a consequence of elevated hyperglycemia and the content of receptor for AGEs in the hippocampus. We found clear peripheral alterations, including hyperglycemia, low levels of proinsulin C-peptide, elevated levels of AGEs in serum and CSF, as well as an increase in RAGE in hippocampal tissue. We found specific astroglial abnormalities in this brain region, such as reduced S100B content, reduced glutamate uptake and increased S100B secretion, which were not accompanied by changes in GFAP. We also observed an increase in the glucose transporter, GLUT-1. All these changes may result from RAGE-induced inflammation; these astroglial alterations together with the reduced content of GluN1, a subunit of the NMDA receptor, in the hippocampus may be associated with the impairment of glutamatergic communication in diabetic rats. These findings contribute to understanding the cognitive deficits in diabetic patients and experimental models.
Assuntos
Astrócitos/metabolismo , Diabetes Mellitus Experimental/metabolismo , Produtos Finais de Glicação Avançada/metabolismo , Hipocampo/metabolismo , Animais , Biomarcadores/sangue , Biomarcadores/líquido cefalorraquidiano , Biomarcadores/metabolismo , Diabetes Mellitus Experimental/sangue , Diabetes Mellitus Experimental/líquido cefalorraquidiano , Produtos Finais de Glicação Avançada/sangue , Produtos Finais de Glicação Avançada/líquido cefalorraquidiano , Masculino , Técnicas de Cultura de Órgãos , Ratos , Ratos Endogâmicos WKY , Subunidade beta da Proteína Ligante de Cálcio S100/sangue , Subunidade beta da Proteína Ligante de Cálcio S100/líquido cefalorraquidiano , Subunidade beta da Proteína Ligante de Cálcio S100/metabolismo , EstreptozocinaRESUMO
Physical exercise effects on brain health and cognitive performance have been described. Synaptic remodeling in hippocampus induced by physical exercise has been described in animal models, but the underlying mechanisms remain poorly understood. Changes in astrocytes, the glial cells involved in synaptic remodeling, need more characterization. We investigated the effect of moderate treadmill exercise (20 min/day) for 4 weeks on some parameters of astrocytic activity in rat hippocampal slices, namely, glial fibrillary acidic protein (GFAP), glutamate uptake and glutamine synthetase (GS) activities, glutathione content, and S100B protein content and secretion, as well as brain-derived neurotrophic factor (BDNF) levels and glucose uptake activity in this tissue. Results show that moderate treadmill exercise was able to induce a decrease in GFAP content (evaluated by ELISA and immunohistochemistry) and an increase in GS activity. These changes could be mediated by corticosterone, whose levels were elevated in serum. BDNF, another putative mediator, was not altered in hippocampal tissue. Moreover, treadmill exercise caused a decrease in NO content. Our data indicate specific changes in astrocyte markers induced by physical exercise, the importance of studying astrocytes for understanding brain plasticity, as well as reinforce the relevance of physical exercise as a neuroprotective strategy.
Assuntos
Astrócitos/fisiologia , Teste de Esforço/métodos , Hipocampo/citologia , Hipocampo/fisiologia , Condicionamento Físico Animal/métodos , Animais , Corticosterona/sangue , Masculino , Ratos , Ratos WistarRESUMO
Diabetes mellitus is a disease associated with several changes in the central nervous system, including oxidative stress and abnormal glutamatergic neurotransmission, and the astrocytes play an essential role in these alterations. In vitro studies of astroglial function have been performed using cultures of primary astrocytes or C6 glioma cells. Herein, we investigated glutamate uptake, glutamine synthetase and S100B secretion in C6 glioma cells cultured in a high-glucose environment, as well as some parameters of oxidative stress and damage. C6 glioma cells, cultured in 12 mM glucose medium, exhibited signals of oxidative and nitrosative stress similar to those found in diabetes mellitus and other models of diabetic disease (decrease in glutathione, elevated NO, DNA damage). Interestingly, we found an increase in glutamate uptake and S100B secretion, and a decrease in glutamine synthetase, which might be linked to the altered glutamatergic communication in diabetes mellitus. Moreover, glutamate uptake in C6 glioma cells, like primary astrocytes, was stimulated by extracellular S100B. Aminoguanidine partially prevented the glial alterations induced by the 12 mM glucose medium. Together, these data emphasize the relevance of astroglia in diabetes mellitus, as well as the importance of glial parameters in the evaluation of diabetic disease progression and treatment.
Assuntos
Neoplasias Encefálicas/metabolismo , Glioma/metabolismo , Glucose/metabolismo , Fatores de Crescimento Neural/metabolismo , Proteínas S100/metabolismo , Acetilcisteína/farmacologia , Neoplasias Encefálicas/patologia , Linhagem Celular Tumoral , Linhagem da Célula , Meios de Cultura , Dano ao DNA , Glioma/patologia , Guanidinas/farmacologia , Humanos , Subunidade beta da Proteína Ligante de Cálcio S100RESUMO
S100B is an astrocyte-derived cytokine implicated in the IL-1beta-triggered cytokine cycle in Alzheimer's disease. However, the secretion of S100B following stimulation by IL-1beta has not been directly demonstrated. We investigated S100B secretion in cortical primary astrocyte cultures, C6 glioma cells and acute hippocampal slices exposed to IL-1beta. S100B secretion was induced by IL-1beta in all preparations, involving MAPK pathway and, apparently, NF-small ka, CyrillicB signaling. Astrocytes and C6 cells exhibited different sensitivities to IL-1beta. These results suggest that IL-1beta-induced S100B secretion is a component of the neuroinflammatory response, which would support the involvement of S100B in the genesis of neurodegenerative diseases.
Assuntos
Hipocampo/efeitos dos fármacos , Interleucina-1beta/farmacologia , Quinases de Proteína Quinase Ativadas por Mitógeno/metabolismo , Fatores de Crescimento Neural/metabolismo , Neuroglia/efeitos dos fármacos , Proteínas S100/metabolismo , Transdução de Sinais/fisiologia , Análise de Variância , Animais , Animais Recém-Nascidos , Células Cultivadas , Córtex Cerebral/citologia , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/farmacologia , Técnicas In Vitro , Indóis , L-Lactato Desidrogenase/metabolismo , Óxido Nítrico/metabolismo , Ratos , Ratos Wistar , Subunidade beta da Proteína Ligante de Cálcio S100 , Transdução de Sinais/efeitos dos fármacos , Frações Subcelulares/efeitos dos fármacos , Fatores de TempoRESUMO
Hippocampal slices have been widely used to investigate electrophysiological and metabolic neuronal parameters, as well as parameters of astroglial activity including protein phosphorylation and glutamate uptake. S100B is an astroglial-derived protein, which extracellularly plays a neurotrophic activity during development and excitotoxic insult. Herein, we characterized S100B secretion in acute hippocampal slices exposed to different concentrations of K(+) and Ca(2+) in the extracellular medium. Absence of Ca(2+) and/or low K(+) (0.2 mM KCl) caused an increase in S100B secretion, possibly by mobilization of internal stores of Ca(2+). In contrast, high K(+) (30 mM KCl) or calcium channel blockers caused a decrease in S100B secretion. This study suggests that exposure of acute hippocampal slices to low- and high-K(+) could be used as an assay to evaluate astrocyte activity by S100B secretion: positively regulated by low K(+) (possibly involving mobilization of internal stores of Ca(2+)) and negatively regulated by high-K(+) (likely secondary to influx of K(+)).
Assuntos
Cálcio/metabolismo , Hipocampo/metabolismo , Fatores de Crescimento Neural/metabolismo , Potássio/metabolismo , Proteínas S100/metabolismo , Animais , Cálcio/farmacologia , Bloqueadores dos Canais de Cálcio/farmacologia , Espaço Extracelular/metabolismo , Ácido Glutâmico/metabolismo , Glutationa/metabolismo , Hipocampo/efeitos dos fármacos , Masculino , Fosfopiruvato Hidratase/metabolismo , Potássio/farmacologia , Ratos , Ratos Wistar , Subunidade beta da Proteína Ligante de Cálcio S100 , Verapamil/farmacologiaRESUMO
Diabetes mellitus is a metabolic disorder that results in glucotoxicity and the formation of advanced glycated end products (AGEs), which mediate several systemic adverse effects, particularly in the brain tissue. Alterations in glutamatergic neurotransmission and cognitive impairment have been reported in DM. Exendin-4 (EX-4), an analogue of glucagon-like peptide-1 (GLP-1), appears to have beneficial effects on cognition in rats with chronic hyperglycemia. Herein, we investigated the ability of EX-4 to reverse changes in AGE content and glutamatergic transmission in an animal model of DM looking principally at glutamate uptake and GluN1 subunit content of the N-methyl-D-aspartate (NMDA) receptor. Additionally, we evaluated the effects of EX-4 on in vitro models and the signaling pathway involved in these effects. We found a decrease in glutamate uptake and GluN1 content in the hippocampus of diabetic rats; EX-4 was able to revert these parameters, but had no effect on the other parameters evaluated (glycemia, C-peptide, AGE levels, RAGE, and glyoxalase 1). EX-4 abrogated the decrease in glutamate uptake and GluN1 content caused by methylglyoxal (MG) in hippocampal slices, in addition to leading to an increase in glutamate uptake in astrocyte culture cells and hippocampal slices under basal conditions. The effect of EX-4 on glutamate uptake was mediated by the phosphatidylinositide 3-kinases (PI3K) signaling pathway, which could explain the protective effect of EX-4 in the brain tissue, since PI3K is involved in cell metabolism, inhibition of apoptosis, and reduces inflammatory responses. These results suggest that EX-4 could be used as an adjuvant treatment for brain impairment associated with excitotoxicity.
Assuntos
Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Experimental/metabolismo , Exenatida/uso terapêutico , Ácido Glutâmico/metabolismo , Animais , Astrócitos/efeitos dos fármacos , Astrócitos/metabolismo , Diabetes Mellitus Experimental/fisiopatologia , Modelos Animais de Doenças , Exenatida/farmacologia , Produtos Finais de Glicação Avançada/metabolismo , Glicosilação , Hipocampo/metabolismo , Masculino , Fosfatidilinositol 3-Quinases/metabolismo , Aldeído Pirúvico/metabolismo , Ratos Wistar , Receptor para Produtos Finais de Glicação Avançada/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Transdução de Sinais/efeitos dos fármacos , Estreptozocina , Transmissão Sináptica/efeitos dos fármacosRESUMO
There is a current interest in dietary compounds (such as trans-resveratrol) that can inhibit or reverse oxidative stress, the common pathway for a variety of brain disorders, including Alzheimer's disease and stroke. The objective of the present study was to investigate the effects of resveratrol, under conditions of oxidative stress induced by H(2)O(2), on acute hippocampal slices from Wistar rats. Here, we evaluated cell viability, extracellular lactate, glutathione content, ERK(MAPK) activity, glutamate uptake and S100B secretion. Resveratrol did not change the decrease in lactate levels and in cell viability (by MTT assay) induced by 1mM H(2)O(2), but prevented the increase in cell permeability to Trypan blue induced by H(2)O(2). Moreover, resveratrol per se increased total glutathione levels and prevented the decrease in glutathione induced by 1mM H(2)O(2). The reduction of S100B secretion induced by H(2)O(2) was not changed by resveratrol. Glutamate uptake was decreased in the presence of 1mM H(2)O(2) and this effect was not prevented by resveratrol. There was also a significant activation of ERK1/2 by 1mM H(2)O(2) and resveratrol was able to completely prevent this activation, leading to activity values lower than control levels. The impairments in astrocyte activities, induced by H(2)O(2), confirmed the importance of these cells as targets for therapeutic strategy in brain disorders involving oxidative stress. This study reinforces the protective role of resveratrol and indicates some possible molecular sites of activity of this compound on glial cells, in the acute damage of brain tissue during oxidative stress.
Assuntos
Antioxidantes/farmacologia , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Peróxido de Hidrogênio/antagonistas & inibidores , Peróxido de Hidrogênio/toxicidade , Estilbenos/farmacologia , Animais , Astrócitos/efeitos dos fármacos , Astrócitos/metabolismo , Astrócitos/patologia , Permeabilidade da Membrana Celular/efeitos dos fármacos , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Ácido Glutâmico/metabolismo , Glutationa/metabolismo , Hipocampo/lesões , Hipocampo/patologia , Técnicas In Vitro , Ácido Láctico/metabolismo , Fatores de Crescimento Neural/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Ratos , Ratos Wistar , Resveratrol , Subunidade beta da Proteína Ligante de Cálcio S100 , Proteínas S100/metabolismoRESUMO
Daily moderate intensity exercise (2 weeks of 20 min/day of treadmill training), which reduces damage to hippocampal slices from rats submitted to in vitro ischemia, did not modify oxidative stress parameters in the hippocampus nor the brain-derived neurotrophic factor (BDNF) levels in different brain regions. The aim was to investigate whether the modulation of hippocampal oxidative status and/or brain BDNF content is involved in exercise-induced neuroprotection. Wistar rats were submitted to daily exercise in the treadmill and were sacrificed approximately 16 h after the last treadmill running. Some several oxidative stress parameters were determined, specifically the free radical levels, the macromolecule damage, the total reactive antioxidant potential and reactivity levels, which represent the total antioxidant capacity, in the hippocampus. In addition, BDNF levels in different rat cerebral regions (hippocampus, cortex, striatum, and the cerebellum) were measured by ELISA. The used exercise protocol did not affect any oxidative stress parameters studied in the hippocampus, suggesting that it does not cause a significant oxidative stress nor induce adaptations of the cellular antioxidant system. Treadmill training also did not change the BDNF content in brain areas studied. Considering the fact that this exercise protocol have been shown to be neuroprotective, we might speculate that BDNF levels and oxidative status may not be directly involved with the mechanisms of exercise-induced neuroprotection after ischemia.
Assuntos
Isquemia Encefálica/metabolismo , Isquemia Encefálica/terapia , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Hipocampo/metabolismo , Estresse Oxidativo/fisiologia , Condicionamento Físico Animal/fisiologia , Animais , Antioxidantes/metabolismo , Encéfalo/anatomia & histologia , Encéfalo/metabolismo , Isquemia Encefálica/fisiopatologia , Citoproteção/fisiologia , Teste de Esforço , Terapia por Exercício/métodos , Radicais Livres/metabolismo , Hipocampo/irrigação sanguínea , Hipocampo/fisiopatologia , Masculino , Técnicas de Cultura de Órgãos , Oxirredução , Consumo de Oxigênio , Ratos , Ratos Wistar , Resultado do TratamentoRESUMO
S100B is a calcium-binding protein, produced and secreted by astrocytes, which has a putative paracrine neurotrophic activity. Clinical studies have suggested that peripheral elevation of this protein is positively correlated with a therapeutic antidepressant response, particularly to selective serotonin reuptake inhibitors (SSRIs); however, the mechanism underlying this response remains unclear. Here, we measured S100B secretion directly in hippocampal astrocyte cultures and hippocampal slices exposed to fluoxetine and observed a significant increment of S100B release in the presence of this SSRI, apparently dependent on protein kinase A (PKA). Moreover, we found that serotonin (possibly via the 5HT1A receptor) reduces S100B secretion and antagonizes the effect of fluoxetine on S100B secretion. These data reinforce the effect of fluoxetine, independently of serotonin and serotonin receptors, suggesting a putative role for S100B in depressive disorders and suggesting that other molecular targets may be relevant for antidepressant activity.
Assuntos
Astrócitos/metabolismo , Fluoxetina/farmacologia , Fatores de Crescimento Neural/metabolismo , Proteínas S100/metabolismo , Inibidores Seletivos de Recaptação de Serotonina/farmacologia , Serotonina/fisiologia , Animais , Astrócitos/efeitos dos fármacos , Células Cultivadas , Ensaio de Imunoadsorção Enzimática , Hipocampo/citologia , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Ratos , Ratos Wistar , Receptores de Serotonina/efeitos dos fármacos , Subunidade beta da Proteína Ligante de Cálcio S100 , Serotonina/farmacologiaRESUMO
S100B is an astrocyte calcium-binding protein that plays a regulatory role in the cytoskeleton and cell cycle. Moreover, extracellular S100B, a marker of glial activation in several conditions of brain injury, has a trophic or apoptotic effect on neurons, depending on its concentration. Hyperglycemic rats show changes in glial parameters, including S100B expression. Here, we investigated cell density, morphological and biochemical alterations in primary cortical astrocytes from rats and C6 glioma cells cultured in high-glucose medium. Astrocytes and C6 glioma cells have a reduced content of S100B and glial fibrillary acidic protein when cultured in a high-glucose environment, as well as a reduced content of glutathione and cell proliferation rate. Although these cells have been used indistinctly to study S100B secretion, we observed a contrasting profile of S100B secretion in a high-glucose medium: a decrease in primary astrocytes and an increase in C6 glioma cells. Based on the in vitro neurotrophic effects of the S100B protein, our data suggest that chronic elevated glucose levels affect astrocyte activity, reducing extracellular secretion of S100B and that this, in turn, could affect neuronal activity and survival. Such astrocyte alterations could contribute to cognitive deficit and other impairments observed in diabetic patients.
Assuntos
Astrócitos/metabolismo , Fatores de Crescimento Neural/metabolismo , Proteínas S100/metabolismo , Animais , Astrócitos/citologia , Linhagem Celular Tumoral , Proliferação de Células , Células Cultivadas , Meios de Cultura/química , Glucose/metabolismo , Ácido Glutâmico/metabolismo , Glutationa/metabolismo , Neuroglia/citologia , Ratos , Ratos Wistar , Subunidade beta da Proteína Ligante de Cálcio S100RESUMO
Bipolar disorder (BD) is a chronic, severe, and highly disabling psychiatric disorder; peripheral markers have been used to assess biochemical alterations associated with BD and/or possibly involved in its pathophysiology. Beyond neuronal commitment, many groups have proposed the involvement of glial activity in psychiatric disorders. Other biochemical markers, particularly associated with oxidative stress, have been studied in BD. In the present study, we evaluated glial involvement and oxidative stress in patients with BD. Glial activity was assessed by measuring serum S100B content; oxidative stress was assessed using serum thiobarbituric acid reactive substances (TBARS) and activities of antioxidant enzymes in BD patients during different episodes of disease. We found a significant increment of serum S100B during episodes of mania and depression, but not in euthymic patients. Superoxide dismutase (SOD) activity, as well the SOD/glutathione peroxidase plus catalase ratio, was also increased in manic and depressed patients. On the other hand, TBARS levels were increased in BD patients regardless of the phase of the disorder. These findings suggest a potential oxidative damage in BD patients. This peripheral oxidative imbalance indicates that systemic changes are taking place during the active phases of the illness. Such changes appear to relate to astrocyte function, as indicated by serum S100B elevation.
Assuntos
Antioxidantes/fisiologia , Transtorno Bipolar/sangue , Transtorno Bipolar/fisiopatologia , Catalase/sangue , Glutationa Peroxidase/sangue , Fatores de Crescimento Neural/sangue , Proteínas S100/sangue , Superóxido Dismutase/sangue , Adulto , Estudos de Casos e Controles , Demografia , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estresse Oxidativo/fisiologia , Subunidade beta da Proteína Ligante de Cálcio S100 , EspectrofotometriaRESUMO
Glial fibrillary acid protein (GFAP) is used commonly as a marker of astrogliosis and astrocyte activation in several situations involving brain injury. Its content may be measured by immunocytochemistry, immunoblotting or enzyme-linked immunosorbent assay (ELISA), usually employing commercial antibodies. Two major post-translational modifications in GFAP (phosphorylation and proteolysis) may alter the interpretation of results or for immunoassay standardization. This study using a non-sandwich ELISA aimed to investigate the putative changes in the immunorecognition due to the phosphorylated state of the antigen by a routinely used polyclonal anti-GFAP antibody from DAKO. Results involving in vitro phosphorylation of purified GFAP or biological samples (brain tissue, cell culture and cerebrospinal fluid) mediated by protein kinase dependent on cAMP indicate that GFAP phosphorylation improves the recognition by the used antibody. These results provide support to the understanding of fast changes in the GFAP-immunoreactivity and suggest that caution is necessary in the interpretation of results using this antibody, as well as indicate that the effect of post-translational modifications must be considered during the standardization of immunoassays with other antibodies.
Assuntos
Astrócitos/fisiologia , Encéfalo/fisiologia , Proteína Glial Fibrilar Ácida/análise , Neuroglia/citologia , Animais , Anticorpos , Astrócitos/citologia , Encéfalo/citologia , Química Encefálica , Córtex Cerebral/citologia , Córtex Cerebral/fisiologia , Ensaio de Imunoadsorção Enzimática , Proteína Glial Fibrilar Ácida/líquido cefalorraquidiano , Proteína Glial Fibrilar Ácida/metabolismo , Cinética , Neuroglia/fisiologia , Fosforilação , Ratos , Ratos WistarRESUMO
The antioxidant compound, trans-resveratrol, is found in substantial amounts in several types of red wine and has been proposed to have beneficial effects in brain pathologies that may involve oxidative stress. The objective of the present study was to investigate the genoprotective effects of resveratrol under conditions of oxidative stress induced by hydrogen peroxide in C6 glioma cells. DNA damage was assessed by the alkaline single-cell gel electrophoresis assay or comet assay. In order to investigate the genoprotective effects of resveratrol against oxidative stress induced by hydrogen peroxide on DNA damage, two models of oxidative stress induction were utilized. (I) 1mM hydrogen peroxide for 0.5h (10-250 microM of resveratrol) and (II) 0.1 or 0.5mM hydrogen peroxide for 6h (10-100 microM of resveratrol). Resveratrol was able to prevent oxidative damage to cellular DNA, induced in model I, at all concentrations tested; however, at 6h of incubation, resveratrol prevented DNA damage only partially. After 6h of incubation (up to 48h) resveratrol per se induced a slight time and dose-dependent DNA damage. In conclusion, these results provide evidence that resveratrol may act as a significantly bioactive compound, supporting the possibility that, due to its antioxidant properties, it may be important in health and disease for protecting against DNA damage through oxidative stress.
Assuntos
Antioxidantes/farmacologia , Dano ao DNA/efeitos dos fármacos , Glioma/patologia , Estresse Oxidativo/fisiologia , Estilbenos/farmacologia , Análise de Variância , Animais , Linhagem Celular Tumoral , Ensaio Cometa/métodos , Dano ao DNA/fisiologia , Relação Dose-Resposta a Droga , Interações Medicamentosas , Peróxido de Hidrogênio/farmacologia , Camundongos , Estresse Oxidativo/efeitos dos fármacos , Propídio , ResveratrolRESUMO
Diabetes mellitus (DM) is a metabolic disorder associated with micro- and macrovascular alterations that contribute to the cognitive impairment observed in diabetic patients. Signs of breakdown of the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCSFB) have been found in patients and animal models of DM. Breakdown of the BBB and BCSFB can lead to disruptions in cerebral homeostasis and eventually neural dysfunction and degeneration. However, our understanding of the biochemistry underlying barrier protein modifications is incomplete. Herein, we evaluated changes in the levels of specific proteins in the BBB (occludin, claudin-5, ZO-1, and aquaporin-4) and BCSFB (claudin-2 and aquaporin-1) in the hippocampus of diabetic rats, and we also investigated the functional alterations in these barriers. In addition, we evaluated the ability of exendin-4 (EX-4), a glucagon-like peptide-1 agonist that can cross the BBB to reverse the functional and biochemical modifications observed in these animals. We observed a decrease in BBB proteins (except ZO-1) in diabetic rats, whereas the EX-4 treatment recovered the occludin and aquaporin-4 levels. Similarly, we observed a decrease in BCSFB proteins in diabetic rats, whereas EX-4 reversed such changes. EX-4 also reversed alterations in the permeability of the BBB and BCSFB in diabetic rats. Additionally, altered cognitive parameters in diabetic rats were improved by EX-4. These data further our understanding of the alterations in the central nervous system caused by DM, particularly changes in the proteins and permeability of the brain barriers, as well as cognitive dysfunction. Furthermore, these data suggest a role for EX-4 in therapeutic strategies for cognitive dysfunction in DM.
Assuntos
Barreira Hematoencefálica/efeitos dos fármacos , Encéfalo/efeitos dos fármacos , Diabetes Mellitus Experimental/metabolismo , Peptídeos/farmacologia , Peçonhas/farmacologia , Animais , Aquaporina 4/metabolismo , Transporte Biológico/efeitos dos fármacos , Barreira Hematoencefálica/metabolismo , Encéfalo/metabolismo , Diabetes Mellitus Experimental/líquido cefalorraquidiano , Exenatida , Masculino , Ratos , Junções Íntimas/efeitos dos fármacos , Junções Íntimas/metabolismoRESUMO
Physical exercise can induce brain plasticity and reduce the cognitive decline observed in type 1 diabetes mellitus (T1DM). We investigated the effects of physical exercise to prevent or reverse spatial memory deficits produced by diabetes and some biochemical and immunohistochemical changes in hippocampal astrocytes of T1DM model. In this study, 56 male Wistar rats were divided in four groups: trained control (TC), non-trained control (NTC), trained diabetic (TD) and non-trained diabetic (NTD). 27 days after streptozotocin-induced (STZ) diabetes, the exercise groups were submitted to 5 weeks of aerobic exercise. All groups were assessed in place recognition (PR) test before and after training. The glial fibrillary acidic protein (GFAP) positive astrocytes were evaluated using planar morphology, optical densitometry and Sholl's concentric circles method. Glucose and glutamate uptake, reduced glutathione (GSH) and glutamine synthetase (GS) levels were measured using biochemical assays. Our main results are: 1-Exercise reverses spatial memory impairments generated by T1DM; 2-Exercise increases GSH and GS in TC but not in TD rats; 3-Exercise increases density of GFAP positive astrocytes in the TC and TD groups and increases astrocytic ramification in TD animals. Our findings indicate that physical exercise reverses the cognitive deficits present in T1DM and induces important biochemical and immunohistochemical astrocytic changes.
Assuntos
Astrócitos/fisiologia , Diabetes Mellitus Experimental/terapia , Diabetes Mellitus Tipo 1/terapia , Terapia por Exercício , Hipocampo/fisiopatologia , Transtornos da Memória/terapia , Animais , Astrócitos/patologia , Glicemia/fisiologia , Peso Corporal/fisiologia , Diabetes Mellitus Experimental/patologia , Diabetes Mellitus Experimental/fisiopatologia , Diabetes Mellitus Experimental/psicologia , Diabetes Mellitus Tipo 1/patologia , Diabetes Mellitus Tipo 1/fisiopatologia , Diabetes Mellitus Tipo 1/psicologia , Proteína Glial Fibrilar Ácida/metabolismo , Glutamato-Amônia Ligase/metabolismo , Ácido Glutâmico/metabolismo , Glutationa/metabolismo , Hipocampo/patologia , Masculino , Transtornos da Memória/patologia , Transtornos da Memória/fisiopatologia , Plasticidade Neuronal/fisiologia , Distribuição Aleatória , Ratos Wistar , Reconhecimento Psicológico/fisiologia , Corrida/fisiologia , Memória Espacial/fisiologiaRESUMO
The majority of Alzheimer's disease (AD) cases are sporadic and aging is the major risk factor for developing the disease, affecting more women than men. In spite of different gender prevalence, most experimental studies in animal models have been performed in male. This study investigates the streptozotocin (STZ)-induced AD model at three different times (2, 4 and 8 weeks afterwards) and in male and female rats, evaluating cognitive deficit, cholinergic neurotransmission, glucose uptake, glutathione content and specific glial markers (GFAP and S100B protein) in the hippocampus of the rat. Our data reinforce the relevance of alterations in STZ model of dementia, reported in the genesis and/or progression of AD such as cholinergic deficit and glucose uptake decrease. All alterations in these parameters (except GFAP) were dependent on sex. It is unclear, at this moment, which alterations are due to sex steroid modulation. In spite of limitations of this experimental model, these data may contribute to understand AD susceptibility and progression dependent on sex.
Assuntos
Doença de Alzheimer/induzido quimicamente , Doença de Alzheimer/patologia , Hipocampo/patologia , Caracteres Sexuais , Animais , Antibióticos Antineoplásicos/toxicidade , Colina O-Acetiltransferase/metabolismo , Modelos Animais de Doenças , Feminino , Proteína Glial Fibrilar Ácida/metabolismo , Glucose/metabolismo , Glutationa/metabolismo , Hipocampo/efeitos dos fármacos , Masculino , Ratos , Ratos Wistar , Reconhecimento Psicológico/efeitos dos fármacos , Subunidade beta da Proteína Ligante de Cálcio S100/metabolismo , Estreptozocina/toxicidade , Fatores de TempoRESUMO
Lipopolysaccharide (LPS) is used to induce inflammation and promotes nervous system activation. Different regions of the brain present heterogeneous glial responses; thus, in order to verify whether systemic LPS-induced inflammation affects the enteric glia differently across the intestinal segments, we evaluated the expressions of two glial activity markers, GFAP and S100B protein, in different intestine segments, at 1h, 24h and 7days after acute systemic LPS administration (0.25 or 2.5mgkg-1) in rats. Histological inflammatory analysis indicated that the cecum was most affected when compared to the duodenum and proximal colon at the highest doses of LPS. LPS induced an increased S100B content after 24h in all three regions, which decreased at 7days after the highest dose in all regions. Moreover, at 24h, this dose of LPS increased ex-vivo S100B secretion only in the cecum. The highest dose of LPS also increased GFAP in all regions at 24h, but earlier in the cecum, where LPS-induced enteric S100B and GFAP alterations were dependent on dose, time and intestine region. No associated changes in serum S100B were observed. Our results indicate heterogeneous enteric glial responses to inflammatory insult, as observed in distinct brain areas.
Assuntos
Ceco/metabolismo , Colo/metabolismo , Duodeno/metabolismo , Proteína Glial Fibrilar Ácida/metabolismo , Inflamação/metabolismo , Lipopolissacarídeos/administração & dosagem , Neuroglia/metabolismo , Subunidade beta da Proteína Ligante de Cálcio S100/metabolismo , Animais , Relação Dose-Resposta a Droga , Inflamação/induzido quimicamente , Lipopolissacarídeos/imunologia , Lipopolissacarídeos/farmacologia , Masculino , Ratos , Subunidade beta da Proteína Ligante de Cálcio S100/sangueRESUMO
BACKGROUND: Inflammatory processes and neural-immune interactions have been implicated in the pathogenesis of psychiatric conditions, but studies in bipolar disorder are inconclusive so far. We aimed to investigate whether peripheral concentrations of C-reactive protein (CRP), an acute-phase response protein of inflammatory activity, are increased in bipolar disorder across the mood spectrum. METHODS: In this systematic review and meta-analysis, we searched MEDLINE, the Cochrane Library, Scopus, and Web of Knowledge from database inception to Aug 14, 2016, for studies that measured serum and plasma CRP concentrations in adult patients with bipolar disorder (as defined by DSM-IV-TR) and healthy controls. We extracted data from published reports. We did three between-group meta-analyses comparing CRP concentrations in patients in mania, depression, or euthymia, with those in healthy controls (cross-sectional studies), and two within-group meta-analyses comparing changes in CRP concentrations before and after treatment of an index manic or depressive episode (longitudinal studies). We used Hedges' adjusted g to calculate effect sizes and pooled results using random-effect models. We also did meta-regression analyses by mood state to investigate possible moderators of CRP concentrations. FINDINGS: We identified 27 studies representing 2161 patients with bipolar disorder and 81â932 healthy controls. Compared with healthy individuals, CRP concentrations were moderately increased in people with bipolar disorder during depression (g 0·67, 95% CI 0·23 to 1·11; p=0·003) and euthymia (0·65, 0·40 to 0·90; p<0·0001) and more substantially increased during mania (0·87, 0·58 to 1·15; p<0·0001). The extent of the increases in CRP concentrations in mania and depression was not related to symptom severity (p=0·256 for mania and p=0·626 for depression). CRP concentrations were moderately decreased after resolution of an index manic episode (-0·36, -0·66 to -0·05; p=0·022) and slightly decreased after resolution of an index depressive episode (-0·18, -0·30 to -0·07; p=0·002). INTERPRETATION: CRP concentrations are increased in bipolar disorder regardless of mood state, but are higher during mania than in depression and euthymia, suggesting an increased inflammatory burden in mania. FUNDING: None.
Assuntos
Transtorno Bipolar/sangue , Transtorno Bipolar/psicologia , Proteína C-Reativa/metabolismo , Humanos , Ensaios Clínicos Controlados Aleatórios como AssuntoRESUMO
Type 1 diabetes mellitus (T1DM) progressively affects cognitive domains, increases blood-brain barrier (BBB) permeability and promotes neurovascular impairment in specific brain areas. Physical exercise, on the other hand, has beneficial effects on brain functions, improving learning and memory. This study investigated the effects of treadmill training on cognitive and motor behavior, and on the expression of proteins related to BBB integrity, such as claudin-5 and aquaporin-4 (AQP4) in the hippocampus and striatum in diabetic rats. For this study, 60 Wistar rats were divided into four groups (n=15 per group): non-trained control (NTC), trained control (TC), non-trained diabetic (NTD), trained diabetic (TD). After diabetic induction of 30 days by streptozotocin injection, the exercise groups were submitted to 5 weeks of running training. After that, all groups were assessed in a novel object-recognition task (NOR) and the rotarod test. Additionally, claudin-5 and AQP4 levels were measured using biochemical assays. The results showed that exercise enhanced NOR task performance and rotarod ability in the TC and TD animals. Diabetes produced a decrease in claudin-5 expression in the hippocampus and striatum and reduced AQP4 in the hippocampus. Exercise preserved the claudin-5 content in the striatum of TD rats, but not in the hippocampus. The reduction of AQP4 levels produced by diabetes was not reversed by exercise. We conclude that exercise improves short-term memory retention, enhances motor performance in diabetic rats and affects important structural components of the striatal BBB. The results obtained could enhance the knowledge regarding the neurochemical benefits of exercise in diabetes.